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pold

Spring clamps instead of spool clamps?

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I don't want to appear arrogant, I deeply value the opinions of you all, experienced and amateurs, otherwise I wouldn't even be asking anything. I am ready to take risks and learn from mistakes. It wasn't difficult to sacrifice a spare rib for an experiment, the rib is still intact after hours, here is some pics I took with a "can of mackerel"...

But you are going to put them on a wider stance (add top/back). That would mean more pressure, and looks like you would max out you opening of the clamps, consider your upraised top/back edges. I'm also concerned that if there is that much pressure (I know its not 25lbs) on the spruce edges (on the corners and sides of the bouts)that it gets a little precarious in that I would worry about it snapping off along the grain line. Try your experiment with top and back first. That would silence me. jeff

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For anyone wishing to make multiple instruments, the investment in a set of top quailty clamps is worth it, but to the amateur who is in it to make one or two for the grandkids, well whatever gets the job done ....

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:) ...I had a chance to use the Herdim clamps for the first time today. Well worth the investment...These make closing much more enjoyable.

When working with older instruments (that often have even more fragile edges), I wouldn't use anything else that I've seen so far.

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But you are going to put them on a wider stance (add top/back). That would mean more pressure, and looks like you would max out you opening of the clamps, consider your upraised top/back edges. I'm also concerned that if there is that much pressure (I know its not 25lbs) on the spruce edges (on the corners and sides of the bouts)that it gets a little precarious in that I would worry about it snapping off along the grain line. Try your experiment with top and back first. That would silence me. jeff

Imagine you put the plate without clamps, that would be the only pressure to add to the clamps, that is almost zero. If you add the plates you are just distributing the pressure over a larger area, I would be worried if I put a microwave on it, but a plate is light as a feather. You can reduce the pressure on the tips just by wrapping insulation tape, rubber, cotton, whatever you want. Consider that in the pics you see, the rib is without linings and the tips of the clamps without any protection, so it was the worst case scenario. For the opening of the jaw I will buy bigger clamps, I need to make sure that the spring is the same as in the medium ones that I used. Before I try them I need to do the plates, I don't know how long is gonna take, I finished the garland (need to trim the linings and level everything) and it took one year (one year of reading this forum).

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I have 8 big clamps so I tried them on a "dummy" half body that I used for varnish assays. the back plate was already glued and you can see the mould is still there. It didn't crash but you can feel quite a lot of pressure. You have to make sure the clamps won't just pop up so that half of the red part of the jaw is on the plate itself.

I suppose you can try with a real body but it seems to me it's too much pressure for what you need.

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I saved up and bought the Herdim clamps and love them. First of all, they work. Second, they work well. Third, I didn't have to do any R&D or test driving. They worked out of the box. Time is money - or in my case as an old fart - short. :rolleyes:

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I have 8 big clamps so I tried them on a "dummy" half body that I used for varnish assays. the back plate was already glued and you can see the mould is still there. It didn't crash but you can feel quite a lot of pressure. You have to make sure the clamps won't just pop up so that half of the red part of the jaw is on the plate itself.

I suppose you can try with a real body but it seems to me it's too much pressure for what you need.

Gosh, I didn't expect to see such a big thing, hahahahaha! Robert try with some pads, rubber, cotton, etc, on the tips, and tell us what you feel.

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I think one can use these, it's just the "what can happen" when you do. I have used these enough to know that they work fine when they do what they are supposed to. I also know that they can damage stuff when they do what they are not supposed to. It is the unpredictability of the nature of a spring loaded clamp that is the problem in my opinion. It is the control of the closing with spool or other ratchet type clamps along with a more stable foot print that makes them a "safer" call...However, who am I to say, I like to live dangerously and I often use tools that are not for the intended use, sometimes because I have to and sometimes because I want to.

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Imagine you put the plate without clamps, that would be the only pressure to add to the clamps, that is almost zero. If you add the plates you are just distributing the pressure over a larger area, I would be worried if I put a microwave on it, but a plate is light as a feather. You can reduce the pressure on the tips just by wrapping insulation tape, rubber, cotton, whatever you want. Consider that in the pics you see, the rib is without linings and the tips of the clamps without any protection, so it was the worst case scenario. For the opening of the jaw I will buy bigger clamps, I need to make sure that the spring is the same as in the medium ones that I used. Before I try them I need to do the plates, I don't know how long is gonna take, I finished the garland (need to trim the linings and level everything) and it took one year (one year of reading this forum).

Maybe I wasn't clear with my concern. It is not for the pressure on the ribs, this is what you illustrated. I'm not worried about that, at all. It's the spruce edges. I guess as long as your clamps bridge over the uplifted edge, and put the pressure over that and onto the area of the top over the ribs, that wouldn't be as bad, certainly couldn't break off the edges that way. Maybe because my only experience are violins that are mainly older, is the reason that this makes me nervous. jeff

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The herdim clamps aren't padded, are they. Also, they are fiddly to get on, being all different shapes, the round ones are just round and they come with pads, much easier.

I used spool clamps for a good number of years. They work fine, but are not idiot proof, by any means... and often do require some fiddling depending on the model instrument being worked on. I prefer the ones that come with the neoprene pads, but they can slide a tad more than leather pads on some fiddles.

No, Herdim clamps aren't padded. They're made of a semi rigid material. Nice feature is that glue doesn't stick to them (they are easy to clean). The reason I like them, especially for repair, is that the clamping pressure is directly above the ribs and a channel clears the edge (no pressure there). Also, due to the design, they engage the outside of the edge (they rest against it preventing them from crawling toward the body & the screw barrel never gets too close to the edge) and they aren't round (so they never touch the arching on a high arched model instrument). I personally have no difficulty with the shapes. They're color coded... brainless. The nuts are knurled (ridged) and easy to adjust. Frankly, I believe I can fit up a round of the Herdim clamps faster than I could manage the round spool type.

To each his/her own though. Sometimes, it's easier to stick to that one is used to.

Back to the subject of the thread: I think I'd miss the sense and control one gets of tightening the clamps using anything with a spring closure for this particular procdure, but I'm happy to be proved wrong.

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I do violin restorations, and I also do some furniture building and other woodworking. I do use spring clamps for other woodworking, but I would never consider using them as a replacement for spool/Herdim clamps for gluing tops and backs. With the spring clamps, you have absolutely NO control over the amount of pressure. Also, with the spring clamps, you could probably only get one into the c-bout area. I use about 30 spool clamps to glue a top on, with 3 in each c-bout area. Light, even pressure all the way around is the way to go.

I'm using homemade spool clamps, made by cutting 1 1/4" holes from a 3/4" cellular PVC trim board with a hole saw. The cut out "holes" are 1 1/8" diameter, with a 1/4" hole in the center. I pad the faces with textured neoprene for slip resistance, and I put a piece of heat shrink tubing on the bolt to prevent bolt contact with the edge of the instrument. The bolts are 4" x 1/4" carriage bolts, with wing nuts.They work great for me. If I come up with some extra money to play with, I may invest in a set of Herdim clamps. They really are the best.

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I consider them "dangerous" simply for the fact that both the top and the back have a slope based on the arch, therefore the clamp feet are not sitting "flat"....The traction on the feet is compromised by not sitting flat, so even if you get them to "stay" a very slight bump /movement, or even on there own accord....they can "fly" off.....when they fly off they return to the closed position, when they do so, it is "random chaos" as they close....best case scenario, they just fly off.....next, they damage the edge....after that, perhaps flying off, knocking over a jar of spirit varnish 10 feet away, knocking it into a space heater, thus setting the shop on fire....Think it hasn't happened?...think again. Personally I approach any project as if I were 1. an insurance adjuster 2. an OSHA inspector 3. the owner of the company trying to minimize loss. Some may call it paranoid I consider it playing it safe

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I am looking forward to finishing the plates and try those clamps. Judging by the pics Robert posted, I would never consider trying them without protection on the tips. I would try the 165mm long with a jaw of 50mm (because there are the 210mm long as well). Insulation tape it's quite soft, rubber inside to create a bump, so they stay stable on the edge without getting close to the arching. I suppose you can cushion the pressure according to the amount of rubber you put, so you can decrease or increase the pressure only in those areas that you want.

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I suppose you can cushion the pressure according to the amount of rubber you put, so you can decrease or increase the pressure only in those areas that you want.

According to my quick scale test ....nope, as the spring jaws open the pressure goes up,it seems in an exponential curve.None of the common padding reduced the pressure at all, in fact, as the jaw opens to accommodate the padding the pressure goes up.Turns out a pounds a pound. :huh:

On craftsmanship .....there is an old axiom that says we should strive to use only just as much force as is needed to have efficiency in our work.As I measured it seems only a few ounces....4-5 maybe a pound on a clamp,

@ 10 lbs per clamp X 30 or so clamps....300#!.or you could just hire a really big guy,or gal to sit...... :o

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Pold, from what's been posted so far, I'm guessing that you could put together proven spool clamps for less money than the spring clamps.

But if you want to defy tradition, and are also willing to put up with the consequences (some of which may not be readily apparent to you), more power to ya.

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as the spring jaws open the pressure goes up

Initially the jaw goes up, then goes down compressing the pad itself....anyway, I am just speculating :blink:

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Pold, from what's been posted so far, I'm guessing that you could put together proven spool clamps for less money than the spring clamps.

But if you want to defy tradition, and are also willing to put up with the consequences (some of which may not be readily apparent to you), more power to ya.

hahaha, yes, it looks like until I don't see some cracks in the plate I am not satisfied...but I'll be as careful as I can, I don't want to waste the expensive wood I bought from Ciresa, this might be my first and last violin.

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I do violin restorations, and I also do some furniture building and other woodworking. I do use spring clamps for other woodworking, but I would never consider using them as a replacement for spool/Herdim clamps for gluing tops and backs. With the spring clamps, you have absolutely NO control over the amount of pressure. Also, with the spring clamps, you could probably only get one into the c-bout area. I use about 30 spool clamps to glue a top on, with 3 in each c-bout area. Light, even pressure all the way around is the way to go.

I'm using homemade spool clamps, made by cutting 1 1/4" holes from a 3/4" cellular PVC trim board with a hole saw. The cut out "holes" are 1 1/8" diameter, with a 1/4" hole in the center. I pad the faces with textured neoprene for slip resistance, and I put a piece of heat shrink tubing on the bolt to prevent bolt contact with the edge of the instrument. The bolts are 4" x 1/4" carriage bolts, with wing nuts.They work great for me. If I come up with some extra money to play with, I may invest in a set of Herdim clamps. They really are the best.

where did you locate the textured neoprene? thanks.

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where did you locate the textured neoprene? thanks.

I got it as scrap from a gasket manufacturer, so I'm not sure of the original source. The texture is like a fine woven fabric, as if the sheet was molded between two fabric sheets. It's 1/16" thick.

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For my latest batch of Cello spool closing clamps I used nice rubber washers.

Any ideas where to source the nicely machined oversize screw nuts like on the Herdim clamps ?

Ben,

Search under "knurled brass thumb nuts". You can find a supplier close to you.

Bruce

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